Variable compression ratio internal-combustion engine



March 18, 1952 PET|T 2,589,958

VARIABLE COMPRESSION RATIO INTERNAL-COMBUSTION ENGINE Filed Jan. 15, 1949 INVENTOR.

AGT

Patented Mar. 18, 1952 vAnIAnLEYcoMPREssIoN RATIQINTER NAP-COMBUSTION ENGINE Georges- Petit, MontreuilLArgille, France Application January 13, 1949 ,"sria1No. 70,758

In France January 28, 1348 This invention relates to a variable compression ratio internal combustion engine, and more particularly to a control system for varying the internal combustion engine.

Such control systems have already been proposed .but have not proved practical. Theprime object of myinvention is, therefore, to generally improve control systems of the'kind referred toL In one type of prior construction, hydraulic means are used for varying the relative position of the crankshaft of an internal combustion engine. However, this prior construction provides for a hydraulic jack and auxiliary means to be disposed outside the crankcase, thus complicating the mechanism considerably. An important object of my invention is to provide hydraulic means of a greatly simplified design.

To the accomplishment of the foregoing objects and such other objects as will hereinafter appear, my invention consists in a control system for the ratio of compression of internal combustion engines, the elements of this control system and their relation one to the other, as hereinafter are more particularly described in the specification and sought to be defined in the claims. The specification is accompanied by a drawing illustrating an engine according to my invention.

Referring now to the drawing, I is the combustion chamber of the motor cylinder 2 within which the piston 3 moves up and down. The crank shaft actuating the piston is designated 4. An oscillatingly carried mounting or cradle 5 supporting the crank shaft 4 is pivoted at one of its ends to a shaft 6 carried by the crank case, the purpose of the cradle being to vary the position of the crank shaft relative to the cylinder block. At its other end, the cradle is linked by means of a connecting rod I to a hydraulic jack. Within the cylinder 8 of the jack, the plunger 9 is moved by oil pressure. An oil pump I8 of any suitable construction supplies oil from the crank case compression ratio of a cylinder and piston type '2Claims. (01.123 48) the pressure prevailingin the intake manifold of the engine, the intake manifold being in communication with the device l4 through the line Hi.

The following is a description of theoperation.

' of my control system. The view illustrated in the drawing may be supposed to correspond to 1 a position of equilibrium so that the oil pressurein the cylinder 8 holds the cradle in equilibrium.- Uponincreasing the speed of the engine, the rod Il descends and acts on the lever I3 and causes the valve Ill to open, thus increasing the flow of oil and decreasing the pressure in the cylinder 8. The plunger 9 descends and so does the cradle, causing the volume of the compression chambers to increase. The rod I1 will come to a standstill in a position which corresponds to the actual load of the engine while, however, the downward movement of the plunger 9 continues until the lever I3 has assumed the same angular through the line I9, forcing oil through the orifice 20 into the cylinder 8.

The oil pressure in the cylinder 8 is regulated. by a valve I0, which, for instance, may be accom-' that can be adjusted by means of a screw nut I2. The lever I3 is operated by the rod I! of a vacuurnresponsive device It which comprises a plston or diaphragm acted upon by a spring I5 and" position in relation to the rod I! as occupied initially. This restores the initial oil pressure "and the equilibrium of the cradle.

A reduction of the speed of the engine causes the upward movement of the rod I! and closes the valve I0 partially or completely. The oil pressure in the cylinder 8 increases, causing the plunger 9 and the cradle to rise, and resulting in a decrease of the volume of the compression chambers. The ascending movement continues until the lever l3 reaches its initial position relative to the rod I1.

When the engine is stopped, both the rod 11 and the plunger 9 of the fluid jack will assume their lowermost positions.

When starting the engine, the rod I'I assumes a position which corresponds to the suction efiect prevailing in the intake manifold. The oil pump 18 causes the pressure in the cylinder 8 to rise, thus causing the upward movement of the plunger 9, and consequently reducing the dead space in the motor cylinder, until the lever I3 meets the rod I1 and equilibrium is established.

The novel and improved control system of my present invention and the advantages in the use and operation thereof will, I believe, be fully apparent from the above detailed description there- "of. It will be further apparent that many changes connecting said fluid jack with said mounting, a vacuum-responsive device operative from the intake manifold to control the operation of the fluid jack, a system for supplying fluid to the jack, the vacuum-responsive;,device communicating with the intake manifold and being provided with suction-operable means, the fluid jack having a plunger provided with a :valve opening and closing the fluid supply circuit, said plunger being connected to said mounting for elevating and lowering the crankshaft, said valve bein normally closed by means resilient means, a lever fulcrumed on said plunger to control, when actuated, said valve, said suction-operable means actuating said lever, said crankshaft, mountin fluid jack, means connecting the fluid jack and mounting, and vacuum-responsive device-being enclosed within the walls of 'the cylinder block and the crankcase.

2. In a cylinder and pisto'n'type of internal combustion engine, an 'intake maniiold, a crankshaft, a mounting to vary the position of the crankshaft relative to the cylinder block, a fluid jack to actuate said mou1rting,ineans operatively connecting said fluid jack with said mounting, avacuum-responsive device operative irom the intake manifold to control the-operation of the fluid jack, a system for supplying fluid to the jack, the vacuum-responsive device communicating with the intake manifold and being provided with suction-operable means, the fluid jack having a plunger provided with a valve opening and closing the fluid supply circuit, said valve being accommodated in the plunger, said plunger being; connected to said mounting for elevating and lowering the crankshaft, said valve being normally closed by means of resilient means, a lever vfu'lcrumed on said plunger to control, when actuated, said valve, said suction-operable means actuating said lever, said crankshaft, mounting, fluid ,jack, means connecting the fluid jack and mounting, and vacuum-responsive device being enclosed within the walls of the cylinder block and the crankcase.

GEORGES PETIT.

7 REFERENCES CITED Thefollowing references are of record in the file of this patent:

UNITED STATES PATENTS 

